Mentally exhausted

I found out my ex gf was diagnosed with cancer again. I’m about to be married in a couple of months and I feel bad for my ex gf, life has been unfair to her. She’s lost her job, health and lover in such a quick time. My fiancé is very supportive and has asked me to be there for her whenever she needs me and I’m glad she feels that way. Ex begins her treatment soon, even now she required blood transfusion for the biopsy, I am fasting for lent today and I broke it and ate food just in case she needed blood. I’m absolutely feeling broken right now and I don’t know how to feel or what to do. I haven’t cried this much since my mom was diagnosed back in 2017.